1. Field of the Invention
This application relates to a hang-up prevention (anti-lodgment) arrangement for fire protection sprinklers. More specifically, the following disclosure addresses the prevention of lodgment of elements which are ejected from the sprinkler upon its activation. The present application also relates to a pendent fire protection sprinkler with a drop-down deflector. The present application further relates to concealed pendent sprinklers for residential, light hazard, and ordinary hazard applications.
2. Related Art
Fire protection sprinklers conventionally are connected to a conduit to receive pressurized fire-extinguishing fluid, such as water. A typical sprinkler has a base with a threaded portion for connection to the conduit and an output orifice to output the fluid to provide fire control and/or suppression. The output orifice is sealed by a seal cap, which is held in place by a release mechanism. The release mechanism is designed to release the cap under predetermined conditions, thereby initiating the flow of fire-extinguishing fluid. A typical release mechanism includes a thermally-responsive element, e.g., a frangible bulb or a fusible link, and may include a latching mechanism.
A sprinkler may be mounted on a fluid conduit running along a ceiling and may either depend downward from the conduit, which is referred to as a “pendent” configuration, or may be mounted on a wall, a certain distance below the ceiling, which is referred to as a “horizontal sidewall” configuration.
Certain conventional sprinklers have a pair of arms that extend from a base, and connect at a hub. The hub is spaced apart from the output orifice of the base and is aligned with a longitudinal axis thereof. The hub may have a set-screw configured to apply a force to the thermally-responsive element and latching mechanism thereby maintaining the seal cap in a position which seals the output orifice. A deflector may be mounted on the hub, transverse to the output orifice, to provide dispersion of the output fluid.
Other sprinklers have a deflector that is attached by a pair of arms that extend from the base of the sprinkler, but do not meet at a hub. In such sprinklers, the thermally-responsive element holds the seal cap in place without being held in compression by a hub. For example, U.S. Pat. No. 4,976,320 shows a sprinkler having a deflector attached to the body with arms that do not meet at a hub. The arms extend from the sprinkler body, and a drop-down deflector is attached to the sprinkler via two guide pins, which are installed in holes in a bent portion at the bottom of each arm. U.S. Pat. No. 5,664,630 shows another example of a sprinkler with a drop-down deflector.
Hang-up, or lodgment, is defined as a malfunction in the operation of a fire sprinkler which, when under a typical system fluid pressure, experiences the lodging of an operating part (cap, gasket, lever, strut, etc.) on or between the frame, deflector, and/or compression screw, so as to impair the water distribution for a period in excess of 60 seconds. A momentary hesitation of an operating part to clear itself from temporary contact with the frame, deflector, and/or compression screw is not considered a hang-up.
Hang-up is a condition that may cause an alteration in the spray pattern of the sprinkler. Because most sprinklers are approved for use based on their spray pattern, an altered spray pattern caused by hang-up is generally not desired.